High-order transmissive diffraction grating for high-resolution spectral systems

摘要

A mathematical model of the spectral transform implemented in a diffraction grating spectral device based on theprinciples of radio optics, the system approach and the theory of linear systems is presenter in paper. The model is basedon a sequential describing of the optical signal conversion by all elements of the device. The rejection of the principles ofgeometric optics when describing the operation of the device is argued. The proposed model in a strict mathematicalform allows to establish important properties of the spectra in various diffraction orders: a nonlinear relationship of thespatial and frequency scale and a multiple improvement in the spectral resolution with an increase in the number of thediffraction order. In addition, a method has been established for improving the resolution of the device by applyingdiffraction gratings with a modified topology of the location of the strokes, which makes it possible to increase theintensity of the diffracted light into higher diffraction orders. Changing the topology consist in location of the strokes atnot at an equidistant distance, i.e. introduction of spatial modulation. The results of computer simulation of a diffractiongrating with the proposed topology and calculations of the theoretically achievable resolution of device with such gratingare presented. A comparison is made between ordinary and high-order diffraction gratings according to their efficiency.